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#41
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Cam companies have known about and been playing game with this for a very long time. In the late '60s I had an Engle solid cam for a SBC that had 0.012" Intake valve lash. 0.012" / 1.5 = 0.008" almost the same as a hydraulic cam. There are still tight lash solid cams available today. Stan PS - Let me also add that using tight lash ramps is one to make a solid cheater cam that will improve performance while still having the same lobe lift and 0.050" duration as the original cam. Also some place (like SCCA) don't let you vary anything or it is illegal
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Stan Weiss/World Wide Enterprises Offering Performance Software Since 1987 http://www.magneticlynx.com/carfor/carfor.htm David Vizard & Stan Weiss' IOP / Flow / Induction Optimization - Cam Selection Software http://www.magneticlynx.com/DV Download FREE 14 Trial IOP / Flow Software http://www.magneticlynx.com/DV/Flow_..._Day_Trial.php Pontiac Pump Gas List http://www.magneticlynx.com/carfor/pont_gas.htm Using PMD Block and Heads List http://www.magneticlynx.com/carfor/pont_pmd.htm Last edited by Stan Weiss; 09-22-2022 at 12:39 PM. |
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#42
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Bottom line regarding Larry's statement.....
In short, when going from a hydraulic lobe to a solid lobe you add duration. .
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'70 TA / 505 cid / same engine but revised ( previous best 10.63 at 127.05 ) Old information here: http://www.hotrod.com/articles/0712p...tiac-trans-am/ Sponsor of the world's fastest Pontiac powered Ford Fairmont (engine) 5.14 at 140 mph (1/8 mile) , true 10.5 tire, stock type suspension https://www.youtube.com/watch?v=qDoJnIP3HgE Last edited by Steve C.; 09-22-2022 at 01:50 PM. |
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#43
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Here is part of my confusion: That 345hp.
For 1969, 345hp meant a Firebird RA4. For 1970, 345hp meant a Firebird RA3. For 1970 RA3, Angeles-McCarthy's 1981 book says 744 cam, but McCarthy's 1989 book says 068 cam as we concluded on this thread (thanks again!) Now more on the ratings confusion. Were road testers early in 1970 mixing up the 345hp Firebird? Or even writers later on? For example, in Chestnut's Kindle book, he refers to the Feb 1970 Hot Rod "345hp" car as a RA4, ie the 1969 rating. Mike Noun's list has a Feb 1970 Motor Trend Firebird RA4 at 14.50 at 99. Both of those seem early for a RA4, since the 1970 Firebird didnt debut until Feb 1970, and none of the early writeups I have even refer to a 370hp Firebird or RA4. The earliest 1970 Firebird writeups I have say 330hp, 335hp, and 345hp, same ratings as the 1969 engines. Maybe the writers were confused, or did the ratings later change to 330, 345, and 370 for those same respective engines? If so, when? Other writeups say 330hp and 345hp, but no mention of 370hp or the RA4 (Firebird). Could it be that the RA4 Firebird didnt come out until later in 1970? So those early road tests had to be RA3 cars? Could it further be that Pontiac slipped the 744 cam into the early 1970 Firebird RA3 cars because there was no RA4 Firebird yet? A bunch of questions on a confusing issue. To me anyway! EDIT: I found this 18 year old thread here, says the RA4 didnt come out until late 1970, and only built in TransAms. Formula could be had with a RA4 but none were ordered. https://forums.maxperformanceinc.com....php?p=2226748 Last edited by ursusarctos; 09-22-2022 at 03:09 PM. |
#44
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The fact is and the bottom line is that the RA4 motor in both the A body cars and the F body where the same 370 hp motor, but the throttle opening in the F body RA4 motors was limited to make for that 345 Hp rating.
It was pretty easy for a test driver back then to see the different names on the hood scopes of these cars to know what they where driving, no less taking a look see under the hood. As far as production goes Pontiac like all GM divisions started production of the next years model run in Aug of the previous year which means that development of parts started well before that as can be seen in McCarhy’s second book on page 185 of the one of the first RA4 intakes in 68.
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I do stuff for reasons. Last edited by 25stevem; 09-22-2022 at 03:28 PM. |
#45
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We had a ’69 RAIV Firebird at this year’s race along with 2 - ’68 RAII Firebirds (all are ‘clone’ cars with the ’69 an original 350HO car and the ’68’s 330 hp Firebird 400 cars). All are 4-speed cars with 4.10 rear gears and they are close in weight, but that will vary if any lightening has occurred (removing all the sound deadener, hollowing out the rear seats, amount of fuel, spare tire or no, etc.). We have seen ’69 Birds typically weigh 50 lbs heavier than the '67/'68 birds comparably equipped (3555 lb. avg. for ’68 400 Birds to 3607 lb, avg. for ‘69’s). The RAII ’68 Birds have a minor advantage over the ’69 RAIV in the weight category, but we’ve had 4 RAII’s (2 stick/2 auto) to only 1 RAIV (stick) over the years. I think if there were more ’69 RAIV’s racing, we’d see a tenth or 2 advantage go to the RAIV with its higher lift at the valve (.520” to .470”) and better flowing intakes (240 cfm to 215 cfm). Rick Mahoney’s and Jim Mino’s ’68 RAII’s have run 11.50’s and 11.80’s respectively, and both were the lightest of the ‘68’s weighed over the past 12 years (3480 lbs. each) and best prepared of all the early Birds that have raced. We’ve had half a dozen or so ‘68/’69 regular Firebird 400’s (330 hp) that ran from the mid-14’s to low-13’s due to different levels of tune and engine prep. Interesting that we have not had any '70 RAIII Formulas at the race yet, let alone '71/'72 455HO Formulas. We've had several RAIII '69 GTO's and a '70 Judge, but they were not 'enhanced' for racing.
There are a couple RAIV A-body cars that have run 12-teens at 115+ mph (max effort cars as well) that weigh in the 3800 lb. range, so the GTO’s are putting it down despite 300 lbs. up on the Firebirds. As for the automatic cars, they are supposed to have the 13” ‘5-5’ convertor, but we see many running the 12” from the TH350’s/L88’s/W30/31’s. Mac did say that Pontiac decided not to install a looser convertor in the RA cars as they (PMD engineering) thought most street races started from a roll of 10 – 15 mph and the stock convertor would be quicker in that scenario. Having a RAIV Judge with the TH400 and 13” factory convertor, it is a slug off the line with the best 60’ of 2.05 sec. I know the 12” convertor equipped cars are turning 1.8’s with set-up suspensions. You need to transfer the weight quickly to plant the Wide Oval tires to get those times. Dennis Last edited by SD455DJ; 09-22-2022 at 03:56 PM. |
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#46
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Early 1969 RAIII/ST = 744 Early 1969 RAIII/HT = 068 Late 1969 & 1970 RAIII (all) = 068 I love the sound of a 744 cam - pretty hard to beat. Quote:
But, there was a pre-production RAIV Trans Am in the fleet of cars - that one which I highlighted as red, WAS a RAIV car - the images make it plainly obvious.
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1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) |
#47
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unruhjonny,
"But, there was a pre-production RAIV Trans Am in the fleet of cars - that one which I highlighted as red, WAS a RAIV car - the images make it plainly obvious." Can you clarify a little bit? If you're looking at the Chestnut EBOOK, there is for sure a Ram Air IV car & scoop shown clearly. But I think those are new pictures, as he has done all thru the Ebook (a great effort, but not error-free). In the Brooklands reprint I have of the original 13.90 at 102 article, Hot Rod Feb 1970, the Ram Air Trans Am is white (a different car than Chestnut shows) and there is no detail I can see that shows a RA4. The original text makes note of a 330hp and optional 345hp Ram Air (standard in Trans Am) but no option above that. The RA3 was standard in the Trans Am, right? Then when they note the 13.90 at 102, it says (345hp Ram Air and 4-speed) ie per their own text, the "standard" Trans Am engine, ie the RA3, with a 1969 rating? That plus the link from this forum 18 years back: https://forums.maxperformanceinc.com....php?p=2226748 (Text below) - this is why I wondered, maybe the RA4 was a late-1970 addition to the already-1970-1/2 Firebird? Just trying to sort it all out. #3 Report Post Old 02-25-2004, 01:27 PM 'ol Pinion head 'ol Pinion head is offline Ultimate Warrior Join Date: Apr 2000 Location: INJUN Territory, Red State Merica! Posts: 9,115 Default No such animal. The RA4 engine was only avail during the '70 1/2 Bird production when ordered in a T/A, & that was at the very end of '70 1/2 production. |
#48
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As a disclaimer, all we can do is guess.
Unless you find info, and great photos from the people who were actually at the tests, we are left to guess. Keep in mind they were journalists, not super fans of these cars - so expect some of the minutia to be lost... By my estimation, for the early press gathering, there were three or four performance Firebirds on hand for testing - these cars would be the ones in print for the February/March magazines. 1) white TA; Deluxe interior, no console, pre-production shift knob, no A/C, RAIV, 4spd; 3.90:1(?) gearing (possibly the same car used for advertisement photos) 2) red(?) Formula; deluxe interior, console formula wheel, A/C, std engine, auto 3.08:1(?) gearing 3) blue(maybe??) Formula; RAIII (this car gets very little ink*, but may be the blue Formula used for '70 sales/promo images) 4) yellow Formula; std engine - nothing clearly mentioned about this car. Now, the Trans Am shown on page 34 of the February Hot Rod article is a white car; It seems that same white car is pictured in much better detail in the March Super Stock article. Did you notice that the Trans Am mentioned in the HR article had a non-production 3.90:1 gear set? Non factory gear set, and e/t's a full half second or better than other recorded e/t's from Firebirds for the early articles - that to me says something right there. * = Regarding the untested(?) ram air Formula; the ram air boots shown on page 21 of the Super Stock Magazine issue are clearly pre-production pieces. The HR article mentions a 3.31:1 geared auto Formula (I believe that this was a gear set used on auto/RA cars), while the Super Stock article mentions a four speed 3.90:1 geared Formula (this tells me it's a pre-production car); The oddball test(?) car was the yellow Formula; Other than some photos, this car is a mystery to me. This car has non-production door handles, non-production single chrome rear view mirror shown, and the dealer-install-only hood tach(!); This car is on the cover of the Hot Rod article, and more photos of it are in the April 'Cars' article. Maybe this is the other 3.90 geared four speed Formula?? After these initial articles, it appears as though the red Formula stayed a part of the test fleet, but the TA was changed from a pre-production car to a production car with a console (and the black ball shift knob) for the June print date articles. To punctuate why I believe that the June printed TA was a differnet car than the one shown for February/March magazine articles, and not just a refreshed car, you need not look further than the June 'Car Life' article; Very little is shown, or explained about the TA, but with only a 14.51 @ 99.3mph e/t - it simply has to be a different car. I have read (I cannot recall off hand where), that some of the writers at this time would estimate e/t's - this may serve to explain why the June Car Life, and June Car and Driver magazines had 4/10 of a second difference between them; Surely they wouldn't be the same car...?? I think the red Formula was also the car used fot the single 1971 Firebird road test; It was in a UK magazine, and between the mention of the need for premium fuel, and other photos, it seems to clearly be a 1970 model.
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1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) Last edited by unruhjonny; 09-23-2022 at 01:00 AM. |
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#49
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the Roger Huntington test cars data. Roger was paralyzed from the chest down when he was 15 years old. No way he could drive the test cars. So a driver always drove the test cars and Roger Huntington recorder the test data with a stop watch from the driver's seat. https://www.mmshof.org/index.php/ind...ger-huntington So there are a lot of other external FACTS, not guesses, that you might not be considering in your assumptions. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#50
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The Car Life was 14.40 at ___ MPH? Car & Driver was 14.10 at 103.2mph. That 103.2 is what strikes me as pretty high for the 068 cam, but ok maybe they had just a driver or good weather or both, they don't say. Does the June 70 Car Life car spec out same as the Car & Driver car? Usually in the old road tests (or even old NHRA) if it's a big motor, I look more at MPH & almost ignore ET, traction was so bad that ET could be just about anything +/- 0.5 sec or more. Of course even MPH depended on total race weight, which also drives me nuts cuz often the magazines would list shipping weight, so often not clear what weight they meant. One other hint I realized to look for on the confusing 345hp is: 345hp @ 5400 1969 RA4-041cam 345hp @ 5000 1970 RA3-068 So when the article text says 345@5000, we can at least assume they're AWARE of the 1970 specs & not just using the old 1969 "345hp=RA4" spec. Still not definitive, I just like making sense of the old history. There will never be another era like that! |
#51
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Guess work aside, I really believe that it would be hard to make a strong argument for the early articles and late articles both having the same Trans Am;
These cars debuted in February 1970, and presumably the February/March print date magazine articles were done with pre-production cars built in January or maybe earlier (the press should have seen them prior to the official launch). Most articles state that the RAIII is the top option - some say "top option at this time"; Yet the Super Stock article irrefutably shows a RAIV car - we all know that the production RAIV cars were all July build date cars - so if the pre-production RAIV Trans Am was replaced with a production car -which was probably tested in April or May for the June articles, that puts it clearly in the time frame of RAIV being off the table for '70 Firebirds. Then there are the interior pictures that show differences between the Feb/March and June Trans Am's. I agree that you could have a drastic swing in drivers based on their skill; I also will agree that a RAIII M21 car should be able to muster e/t's better than mid-fourteens...
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1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) |
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#52
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I had thought that Feb 1970 was way too early for a RA4 Firebird. And it would be - in fact most of model year 1970 would be too early. But very possible that the Feb 1970 road tests could be pre-production RA4 cars, and before they even had a rating (which ended up at 370 later on) so the text uses the 345hp RA4 rating of 1969. So that puts the June 1970 Car & Driver test of 14.10 at 103.2 as a RA3-068 car. The 103.2 still seems fast, that's why I wondered what ET_MPH the June 1970 Car LIFE test ran & if it was the same setup or same car. I also dont have the ?month? SuperStock test, can you summarize that car & its ET_MPH? I know sometimes SuperStock would go a little beyond just setting the timing LOL so did they do any of that? Much appreciated I'm starting to get a handle on this. So many 400 variants. |
#53
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June C&D TA interior on the left;
March C&D TA interior on the right: Images of the March SS Trans Am's engine: I nice spread of images from page 21 in the SS article: Unfortunately the article does not seem to test the Trans Am; Instead it compares two Formulas; 1) Red; Auto (std engine w-A/C & 3.08:1 gears): 15.2 @ 92mph 2) "stick shift" with "3.9 rear gear": 14.5 @ 100.5mph The article spends alot of time on the RAIV & RAV stuff, then ends it with the following: Quote:
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1970 Formula 400 Carousel Red paint on Black standard interior A no-engine, no-transmission, no-wheel option car. Quite likely one of few '70 Muncie three speed Formula 400's left. 1991 Grand Am: 14.4 @ 93.7mph (DA corrected) (retired DD, stock appearing) 2009 Cobalt SS: 13.9 @ 103mph (current DD; makes something north of 300hp & 350ft/lbs) |
#54
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I don't see a Ram Air IV on that scoop - maybe the prototype RA4 car didnt have the fancy lettering? That would mean that in the early magazine articles eg Feb 1970, it could be an RA4 car even if the scoop has no letters on it? From my files it looks like NHRA factored the RA2 at 385hp and the RA4 at 380hp, but essentially "the same" and the 68-RA2 Firebird and 69-RA4 Firebird both ran in the W/P=8.50 class. The 68-RA2 GTO and 69-RA4 GTO both ran in the W/P=9.00 class, so RA2 and RA4 ran heads up against each other in NHRA. |
#55
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In 1970 they didn't put anything on the TA scoop. Didn't matter if it was a 3 or a 4, the scoop was blank in 70 so what you see in the picture is correct.
That TA in the picture, especially with the scoop removed is most definitely a RAIV. You can plainly see the aluminum intake with the separate cast iron heat cross over. A sharp eye can also see the 614 heads in the other pictures. |
#56
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So when we see (modern) pictures of 70 RA4 cars with Ram Air IV on the scoop, this was just recently added as Gratuitous Bling? See below video about 0:35. Also, Chestnut's 50 Fastest Kindle ebook shows a blue 70TA with letters on the scoop too. But those are both "modern" visuals. https://www.youtube.com/watch?v=Aj5pBogZ6nw |
#57
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The factory didn't start doing that until 1971 with 455 HO etc... |
#58
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Not sure about new camshafts, but Leader sent factory RAV camshafts to Crane for regrinding.....
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Hoping to finish a project while I'm still able to push the clutch in.... 1963 Tempest Convertible (195-1bbl, 3-speed transaxle. 428 RAIV, 5-speed, IRS planned) Pictures |
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#59
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All it took was owners over 4 decades ago viewing in print a few black & white pics of a RA IV decal in that spot.
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Buzzards gotta eat... same as worms. |
#60
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I believe that was a pre production test car you're talking about |
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